Will a PO upper (you know, the fly weight ARs) fit on a regular AR15 lower.  Their website says that almost no parts are interchageable, but it didn't specifically list the upper/lower fit.  I just ordered a CavArms lower today and want to make a kite-weight AR.  Appreciate ya.

I don't know if the Po upper off a PO receiver will fit a regular Ar, but i do know PO makes a retrofit carbon upper for regualr AR receiver.

POI uppers from factory built guns WILL NOT fit mil-spec lowers...

The rear takedown hole is in a different location (higher/lower).

I wouldn't recommend using ANYTHING from POI, unless you don't plan to shoot it...

Try looking into Bushmasters new flyweight 16" pencil barrel if you want a lightweight carbine...

Professional Ordnance stuff looks perty, but is junk, junk, junk...

I've owned 2 guns from them, both were absolute shit...
Last one I had, split the bolt in half after only 2 shots from a brand new gun...

Do a search on them, you will see for yourself...

Thanks for the save.